富含活性氯与Al_(13)水处理药剂对铜氰络合物去除效能

含重金属铜离子与氰离子(CN)的络合物广泛存在于电镀、冶金等工业废水中,是一种较难处理的污染物。富含活性氯和Al13聚合体的水处理药剂(PACC)兼具氧化和絮凝效能,在处理含重金属氰络合物([Cu(CN)3]2-)废水方面具有良好的应用前景。研究PACC与[Cu(CN)3]2-的反应计量学、动力学,考察了pH、反应时间和投药量等影响因素,确定PACC的最佳工作参数。结果表明,PACC可同时实现对CN的氧化和对Cu2+的絮凝,有效去除水中[Cu(CN)3]2-。使用PACC对[Cu(CN)3]2-的无害化处置过程分为2个阶段:CN-首先被氧化成氰酸根(OCN-);然后OCN-被进一步氧化并生成碳酸氢根和氮气,同时所释放的游离态铜离子被絮凝去除。这2个阶段反应的最佳pH分别为11和8,去除1 mol[Cu(CN)3]2-的最佳投药量为9.35 mol Cl2的PACC;在此条件下反应43 min后,其出水中CN-和Cu2+的浓度均达到排放标准(GB21900-2008)要求。

Effective treatment of copper-cyanide complex by a novel water treatment reagent

Copper cyanide complexes ([Cu(CN)₃]^2-) are produced in several types of industry that include electroplating,mining,and they are difficult to be removed from wastewater.A novel water treatment reagent containing high content of active chlorine and Al₁₃ polymer (PACC) was prepared by electrochemical method.PACC has shown a promising potential for the removal of metal-cyanide complex due to the combined functions of oxidation and coagulation.In order to determine the optimal working conditions of PACC,stoichiometry and kinetics of the reaction between PACC and [Cu(CN)₃]^2- were investigated,and a series of experiments about pH value,reaction time and dosage effect were carried out.The results indicate that PACC is effective for the treatment of [Cu(CN)₃]^2- through the oxidation of CN^- by active chloride and the subsequent removal of Cu²⁺ by coagulation with Al₁₃ polymer.Two stages were carried out for the complete treatment of [Cu(CN)₃]^2-.CN^- was oxidized to OCN^- in the first stage,then OCN^- was further converted into carbonate and nitrogen and the liberated Cu²⁺ was removed by coagulation in the second stage.The optimal pH values of these two-stages are pH 11.0 and pH 8.0,respectively.The optimal dosage is 9.35 mol Cl₂ PACC for the treatment of 1 mol [Cu(CN)₃]^2-.The reaction time is about 43 minutes under these conditions and the concentration of cyanide and copper both meet the requirement of GB21900-2008.